The secondary literature on Augustine is bewilderingly immense, and generally the man himself is considerably easier to read than his commentators. The first port of call should definitely be the Confessions; after that, The City of God, On Christian Doctrine and his own small ‘systematic theology’, the Enchiridion, are all near ‘musts’ for the thinking Christian.

Augustine: Later Works, Library of Christian Classics (London: SCM, 1955)also contains a collection of highly-readable shorter works (On the Spirit and the Letter, On the Trinity, and Homilies on the Epistle of John), accompanied by excellent explanatory notes. The Homilies on the Epistle of John are particularly stirring, bite-size sermons on his theology of love.

After that, the best introduction to Augustine is his definitive biography, which clearly puts his theology in context, Peter Brown’s Augustine of Hippo (London & Boston: Faber & Faber, 1967). A wonderful read.